What is the principle of microphone and earpiece?

The working principle of the microphone is: when a person speaks into the source microphone, the sound wave causes the diaphragm to vibrate, and the diaphragm squeezes the carbon particles loosely and tightly, and the resistance changes accordingly, producing a resistance in the circuit. The current that changes with sound vibration, that is, the microphone is equivalent to a variable resistor.

The working principle of the earpiece is: when the current that changes in intensity is generated by the vibration of the speaking voice from the microphone, the attraction force of the electromagnet to the iron sheet also changes, causing the iron sheet to vibrate. It produces the same sound as the other party's speaking voice, that is, the earpiece is equivalent to an electromagnet.

A specific form of current (such as the current that the microphone has just "encoded") flows through the coil of the earpiece, which causes the magnetic field generated by the coil to change, so the magnetic force between the permanent magnet and the coil changes. Then the distance between the permanent magnet and the coil will change. This causes the membrane to vibrate and produce sound.

To put it simply: the sound signal is converted into an electrical signal through the electromagnetic coil, and the earpiece converts the received electrical signal into a sound signal through electromagnetism.

Extended information:

The composition of the microphone and earpiece:

The earpiece consists of a magnetic circuit system (permanent magnet, core column, magnetic conductive plate), vibration system ( It consists of three parts: paper cone, voice coil) and support auxiliary system (centering support, basin frame, edge pad).

1. Voice coil: The voice coil is the driving unit of the cone-shaped paper cone earpiece. It is made of very thin copper wires wound on the paper tube in two layers, usually dozens of times, also known as The coil is placed in the magnetic gap formed by the magnetic core column and the magnetic plate. The voice coil and the paper cone are fixed together. When the sound current signal passes into the voice coil, the vibration of the voice coil drives the paper cone to vibrate.

2. Paper cone: There are many types of materials used in the cone-shaped diaphragm of the cone-shaped paper cone earpiece, generally including natural fibers and man-made fibers. Natural fibers often use cotton, wood, wool, silk, etc., while man-made fibers use rayon, nylon, fiberglass, etc.

Since the paper cone is the sound radiation device of the earpiece, it determines the sound emission performance of the earpiece to a considerable extent. Therefore, no matter what kind of paper cone, it is required to be both light and rigid. Deformation due to changes in ambient temperature and humidity.

3. Folding ring: The folding ring is set up to ensure the axial movement of the paper cone along the earpiece and limit the lateral movement. It also blocks the air circulation in the front and rear of the paper cone. In addition to the commonly used paper cone materials, the folding ring materials also use plastic, natural rubber, etc., and are bonded to the paper cone through hot pressing.

4. Centering support piece: The centering support piece is used to support the joint between the voice coil and the paper cone to ensure that it is vertical and not skewed. There are many concentric rings on the centering support piece, so that the voice coil can move up and down freely in the magnetic gap without lateral movement, ensuring that the voice coil does not collide with the magnetic conductive plate. The dust cover on the centering support piece is to prevent external dust from falling into the magnetic gap, causing friction between the dust and the voice coil, and causing the earpiece to produce abnormal sounds.